Suction muffler for a reciprocating hermetic compressor

ABSTRACT

A suction muffler for a reciprocating hermetic compressor, comprising a hollow body ( 10 ) provided with a gas inlet and a gas outlet ( 12, 14 ), which are respectively in fluid communication with the gas supply to the compressor and with a suction side thereof, said hollow body ( 10 ) defining a plurality of chambers comprising an innermost first acoustic chamber ( 50 ) in fluid communication with the gas outlet ( 14 ) of the hollow body ( 10 ), and a second acoustic chamber ( 51 ) surrounding at least partially the first acoustic chamber ( 50 ) and in fluid communication with at least one of the parts defined by said first acoustic chamber ( 50 ) and by the gas inlet ( 12 ) of the hollow body ( 10 ).

FIELD OF THE INVENTION

[0001] The present invention refers to a suction muffler for areciprocating hermetic compressor, particularly of the type used insmall refrigeration systems in the region where the refrigerant gas issupplied to the hermetic compressor.

BACKGROUND OF THE INVENTION

[0002] As a rule, the reciprocating hermetic compressors present, at thesuction side thereof, an acoustic dampening system (acoustic filters orsuction mufflers), which is provided inside the shell and which conductsthe gas coming from the suction line to the suction valve.

[0003] This component has several important functions to the adequateoperation of the compressor, such as gas directing, acoustic dampeningand, in some cases, thermal insulation of the gas being drawn into thecylinder.

[0004] The adequate thermal insulation of the gas being drawn isimportant to improve the volumetric and energetic efficiencies of thecompressor.

[0005] During the time elapsed between the admission to the compressorand the admission to the cylinder thereof, the gas temperature isincreased, due to heat transferred thereto from the several hot sourcesexisting inside the compressor. The temperature increase of the gascauses an increase in its specific volume and consequently reduces themass flow of the refrigerant pumped by the compressor. Since therefrigeration capacity of the compressor is directly proportional to themass flow, reducing said flow results in efficiency loss.

[0006] In order to achieve adequate thermal insulation, the currentmufflers are usually produced in a material of low thermal conductivity,such as for example, resins, plastic, having good thermal insulationproperty.

[0007] There are known in the art the suction mufflers constructed ofinjected plastic material and comprising a hollow body, which isprovided with gas inlet and gas outlet nozzles and, internally, with aplurality of chambers disposed in a consecutive arrangement and in alinear sequence, and which are maintained in fluid communication inrelation to each other and to the gas inlet of the compressor through aduct having an end connected and opened to the gas inlet nozzle of thehollow body; median windows, which are longitudinally spaced from eachother and opened to respective chambers; and an opposite end opened to alast chamber of the linear sequence and which is maintained opened tothe gas outlet of the hollow body.

DISCLOSURE OF THE INVENTION

[0008] It is an object of the present invention to provide a suctionmuffler for a reciprocating hermetic compressor, which does not presentthe inconveniences of the known prior art solutions and which producesimproved noise attenuation with reduced heating of the gas admitted tothe compression cylinder.

[0009] This and other objects are achieved by a suction muffler for areciprocating hermetic compressor, comprising a hollow body providedwith a gas inlet and a gas outlet, which are respectively in fluidcommunication with the gas supply to the compressor and with a suctionside of the latter, the hollow body of said muffler defining a pluralityof chambers comprising a first innermost acoustic chamber in fluidcommunication with the gas inlet and the gas outlet of the hollow body,and a second acoustic chamber, surrounding at least partially the firstacoustic chamber and in fluid communication with at least one of theparts defined by said first acoustic chamber and by the gas inlet of thehollow body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The invention will be described below, with reference to theattached drawings, in which:

[0011]FIG. 1 is an exploded perspective view of a construction for thesuction muffler of the present invention;

[0012]FIG. 2 is a vertical cross-sectional view of the suction mufflerof FIG. 1 in the assembled condition;

[0013]FIG. 3 is a lateral longitudinal sectional view of the suctionmuffler of FIG. 2 in the assembled condition; and

[0014]FIG. 4 is a horizontal cross-sectional view of the suction mufflerof the present invention; Description of the Illustrated Embodiment

[0015] As illustrated in the appended drawings, the suction muffler ofthe present invention comprises a hollow body 10 usually obtained in amaterial of low thermal conductivity, for example with a rectangularcross-section, and which is closed by an upper cover 10 to be seated onthe upper edge of the hollow body 10 and there affixed by any adequatemeans, such as for example a pair of clamps 30 fitted by elasticdeformation into respective lugs 11 and 21 provided in both the hollowbody 10 and the cover 20.

[0016] The hollow body 10 is provided with a gas inlet 12, in fluidcommunication with the gas supply to the compressor and aligned with thesuction tube of the compressor (not illustrated), and a gas outlet 14 influid communication with the suction side of the compressor.

[0017] The cover 20 incorporates, superiorly and externally, a gasoutlet nozzle 22, in the form of a tubular extension, with its free endshaped to be adapted to the suction orifice of a valve plate 40 of thehead of the hermetic compressor.

[0018] According to the present invention, the hollow body 10 defines aplurality of chambers, disposed in surrounding superposed layers, forexample in an eccentric arrangement, comprising a first innermostacoustic chamber 50 in fluid communication with the gas inlet 12 and thegas outlet 14 of the hollow body 10, and a second acoustic chambersurrounding at least partially the first acoustic chamber 50 and influid communication with at least one of the parts defined by said firstacoustic chamber 50 and by the gas inlet 12 of the hollow body 10.

[0019] In the illustrated constructive form, the hollow body 10 definesonly two acoustic chambers, the second acoustic chamber 51 beingmaintained in direct fluid communication with the gas inlet 12 and inrestrict and pressure equalizing fluid communication with the inside ofthe compressor shell.

[0020] As illustrated, the hollow body 10 is provided, in a lower wall10 a, with a restricting orifice 15, for drainage of lubricant oil andby which is obtained said pressure equalization.

[0021] In the illustrated construction, the first acoustic chamber 50 isdefined internal to a shell 60, which is formed for example by atwo-piece body and provided inside the hollow body 10, the secondacoustic chamber 51 being defined external to said shell 60 and internalto said hollow body 10.

[0022] According to a constructive option illustrated in the presentinvention, the fluid communication between the first and the secondacoustic chambers 50, 51, is maintained through a first duct portion 70,which is provided through the second acoustic chamber 71 and connectedto the gas inlet 12 of the hollow body 10 and provided with at least onewindow 72, which is opened to the second acoustic chamber 51 and throughwhich is achieved the direct fluid communication between said secondacoustic chamber and the gas inlet 12 of the hollow body 10. Althoughnot illustrated, the second acoustic chamber 51, in a constructiveoption of the present invention, may keep direct fluid communicationwith the first acoustic chamber 50, being provided in a wall of theshell 60, maintaining indirect fluid communication with the gas inlet 12of the hollow body 10, or may be also defined, in anothernon-illustrated constructive option, by the discontinuity of the duct40, communicating said gas inlet 12 with the first acoustic chamber 50.

[0023] According to the present invention, the plurality of chambers ofthe hollow body 10 may further comprise (though not illustrated) atleast one heat insulating chamber, which is provided in order tosurround, at least partially and adjacently, at least one of the firstand second chambers 50, 51, each heat insulating chamber beingmaintained only in restrict and pressure equalizing fluid communicationwith the inside of the shell (60) of the compressor. This equalizingfluid communication can be obtained, for example, by a restrictingorifice provided in each chamber, for allowing the oil to pass from theinnermost chamber to the outermost chamber and thence to the shell ofthe compressor.

[0024] In the construction presenting heat insulating chambers, thefirst duct portion 70 is continuous through said heat insulatingchamber, in order to prevent the gas admitted by said first duct portion70 from reaching the internal volume of these chambers. In theconstructions in which the hollow body 10 presents acoustic chambersonly, such as in the illustrated construction, each one of thesurrounding chambers also defines a respective heat insulating chamberin relation to the surrounded chamber.

[0025] According to the present invention, the first acoustic chamber 50is maintained in fluid communication with the gas outlet 14 of thehollow body 10 through a second duct portion 71 tightly mounted into anoutlet orifice 61 of the shell 60 dimensioned for the tight passage ofan inlet end 71 a of the second duct portion 71 and opened to the insideof the first acoustic chamber 50, upon mounting said second duct portion71 inside the first acoustic chamber 50. The second duct portion 71presents a certain preferred extension, for instance substantiallyrectilinear which, as illustrated, is provided inside the first acousticchamber 50, so that the respective inlet end 71 a thereof is disposedclose to an outlet end 70 a of the first duct portion 70, terminating,for example, in the form of a deflector and having its axis parallel tothe axis of said inlet end 71 a.

[0026] Although not illustrated, other constructions and arrangementsare possible for the second duct portion with variations in the shape(not rectilinear), extension and positioning of said portion inside thefirst acoustic chamber 50, without said modifications affecting theperformance of the suction muffler of the present invention.

[0027] As illustrated, the first duct portion 70 is incorporated to thewalls of the first acoustic chamber 50, which is for example in twopieces, with each half of its body being adjacent to an enlarged upperportion 50 of the first acoustic chamber 50, in order to define arespective half of the extension of said first duct portion 70.

[0028] According to the embodiment of the present solution illustratedin the enclosed figures, the shell 60 carries in a gas inlet 62, anozzle in the shape of a cornet 64 opened to the inside of thecompressor and aligned with the suction tube.

[0029] In this construction, the first duct portion 70 presents a window72 defined by an extension discontinuity in one of the walls of the bodyof the first acoustic chamber 50 that defines a corresponding extensionof said first duct portion 70.

[0030] In the illustrated construction, the parts of the body definingthe first duct portion 70 are seated and attached to each other, bybeing fitted inside the walls of the adjacent surrounding chamber, whichin this construction is the second acoustic chamber 51. The fixationbetween the parts defining the body of the first duct portion 70 isachieved by fitting a guide element 80 provided in one of the partsdefined by the hollow body 10 and the shell 60, for example in anexternal wall of one of the parts of said first acoustic chamber 50,into a rail (not illustrated) provided in the other of said parts, forexample in one of the internal walls of the second acoustic chamber 51.

[0031] According to the present invention, the gas admitted by thesuction muffler through the cornet 64 is directly conducted to theinside of the first acoustic chamber 50, from which it is drawn to theinside of the compressor cylinder (not illustrated) by means of thesecond duct portion 71.

[0032] The arrangement of the surrounding chambers of the presentinvention increases the resistance to the transfer of heat generated bythe compressor and transmitted to the gas drawn thereby, since the gasflow has to cross the wall of each outermost chamber, which is usuallyin a material of low thermal conductivity, the thickness of the gas masscontained in the outermost chamber, and the wall of the innermostchamber, before reaching the innermost acoustic chamber and thence theinterior of the cylinder.

[0033] Moreover, the geometry of the innermost acoustic chamber allowsthe temporary formation of a cold gas volume, available to suction,which allows the acoustic effect of cylinder over-filling, improving thecompressor efficiency.

[0034] A further advantage of the present solution is that thearrangement of the surrounding chambers allows the noise transmission tobe attenuated in the direction of transmission. Part of the noisegenerated by operation of the suction valve is transmitted by the wallsthat form the muffler, which vibrate upon operation of the compressor.Thus, the existence of a gas volume between the immediately adjacentwalls of the chambers of the present construction attenuates saidtransmission.

1. A suction muffler for a reciprocating hermetic compressor, comprisinga hollow body (10) provided with a gas inlet and a gas outlet (12, 14),which are respectively in fluid communication with the gas supply to thecompressor and with a suction side thereof, characterized in that thehollow body (10) defines a plurality of chambers comprising an innermostfirst acoustic chamber (50) in fluid communication with the gas outlet(14) of the hollow body (10), and a second acoustic chamber (51)surrounding at least partially the first acoustic chamber (50) and influid communication with at least one of the parts defined by said firstacoustic chamber (50) and by the gas inlet (12) of the hollow body (10).2. Muffler, according to claim 1, characterized in that the fluidcommunication between the first and second acoustic chambers (50, 51) ismaintained through a first duct portion (70), which is provided throughthe second acoustic chamber (51), connected to the gas inlet (12) of thehollow body (10) and having at least one window (72) opened to thesecond acoustic chamber (71).
 3. Muffler, according to claim 2,characterized in that the plurality of chambers further comprises atleast one thermal insulating chamber, which is provided in order tosurround, at least partially and adjacently, at least one of the firstand second acoustic chambers (50, 51), each thermal insulating chamberbeing maintained only in restrict and pressure equalizing fluidcommunication with the inside of the shell of the compressor. 4.Muffler, according to claim 3, characterized in that the first ductportion (70) is continuous through the thermal insulating chamber. 5.Muffler, according to any of claims 1 to 5, characterized in that thefluid communication between the first acoustic chamber (50) and the gasoutlet (14) of the hollow body (10) is maintained through a second ductportion (71).
 6. Muffler, according to claim 5, characterized in thatthe first duct portion (70) extends to the inside of the first acousticchamber (50).
 7. Muffler, according to claim 6, characterized in thatthe second duct portion (71) has a substantial part of its extensioninside the first acoustic chamber (50).
 8. Muffler, according to claim7, characterized in that the first duct portion (70) has an outlet end(70 a) provided close to an inlet end (71 a) of the second duct portion(71).
 9. Muffler, according to claim 8, characterized in that the outletend (70 a) of the first duct portion (70) has its axis parallel to thatof the inlet end (71 a) of the second duct portion (71).
 10. Muffler,according to claim 9, characterized in that the second duct portion (71)is rectilinear in a substantial part of its extension internal to thefirst acoustic chamber (50).
 11. Muffler, according to claim 10,characterized in that the first duct portion (70) is incorporated inpart of the walls which define the first acoustic chamber (50). 12.Muffler, according to claim 11, characterized in that the outlet end (70a) of the first duct portion (70) is in the form of a deflector. 13.Muffler, according to claim 12, characterized in that the first acousticchamber (50) is defined inside a shell (60) formed in two pieces, whichare seated and affixed to each other and provided inside the hollow body(10).
 14. Muffler, according to claim 13, characterized in that thefixation between the two pieces of the body of the shell (60) isobtained upon being fitted inside the walls of the adjacent surroundingchamber.
 15. Muffler, according to claim 14, characterized in that saidfixation is achieved by fitting a guide element (80) provided in one ofthe parts defined by the hollow body (10) and the shell (60) into a railprovided in the other of said parts.
 16. Muffler, according to claim 15,characterized in that the second acoustic chamber (51) is definedexternal to the shell (60) and internal to the hollow body (10). 17.Muffler, according to claim 1, characterized in that the chambers areeccentrically provided.